Chiral recognition in aqueous solutions. Preferential configurations of ?-aminoacids bearing substituted alkyl chains at 25�C

1995 ◽  
Vol 24 (12) ◽  
pp. 1209-1217 ◽  
Author(s):  
Giuseppina Castronuovo ◽  
Vittorio Elia ◽  
Filomena Velleca
Keyword(s):  
Aqueous Solutions ◽  
Chiral Recognition ◽  
Alkyl Chains ◽  
Preferential Configurations

scholarly journals Addition Effect of Fatty Alcohol with Long Alkyl Chains on the Size of Oleic Acid Droplets in Aqueous Solutions without Surfactant

2008 ◽  
Vol 81 (4) ◽  
pp. 111-116
Author(s):  
Hidetaka AKATSUKA ◽  
Tadahito SETO ◽  
Mariko HAYASHI ◽  
Toshio SAKAI ◽  
Hideki SAKAI ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Aqueous Solutions ◽  
Fatty Alcohol ◽  
Alkyl Chains

Chiral recognition in solution. Interactions of α-amino acids in concentrated aqueous solutions of urea or ethanol

1999 ◽  
Vol 77 (7) ◽  
pp. 1218-1224 ◽  
Author(s):  
Giuseppina Castronuovo ◽  
Vittorio Elia ◽  
Anna Pierro ◽  
Filomena Velleca
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Chiral Recognition ◽  
Hydrophobic Interactions ◽  
Configuration Model ◽  
Excess Functions ◽  
Interaction Coefficients ◽  
Experimental Conditions ◽  
Concentrated Aqueous Solutions ◽  
The Difference

Enthalpies of dilution of the L and D forms of glutamine, citrulline, and phenylalanine in concentrated aqueous solutions of urea or ethanol were measured calorimetrically at 298 K. Glycine, urea, formamide, and phenol were also studied under the same experimental conditions, to get information about the behaviour of the zwitterion and of the functional group in the side chain of the cited amino acids when the concentration of the cosolvent changes. The derived pairwise enthalpic interaction coefficients for the three amino acids were rationalized according to the preferential configuration model. Indications are that, in concentrated urea, the coefficients for citrulline and glutamine are determined mainly by the interactions between the cosolvent and the hydrophilic groups in the molecule of the amino acids. For phenylalanine, coefficients are less positive than in water, because the presence of urea, which solvates preferentially the zwitterions, attenuates hydrophobic interactions between the benzene rings. In ethanol, coefficients for the three amino acid become negative or more negative than in water, because in this medium hydrophilic interactions are enhanced. Chiral recognition, namely the difference in the values of homo- and heterochiral interaction coefficients, was detected only for phenylalanine in urea. Hence, the nature of the cosolvent, influencing differently hydrophilic and hydrophobic interactions, can lead to the detection of chiral recognition also for those systems that, as phenylalanine, do not present this effect in pure water.Key words: α-amino acids, excess functions, molecular interactions, preferential configuration.

Chiral recognition in aqueous solutions at 25 °C. A calorimetric study of the interaction between enantiomeric α-amino acids of different alkyl chain length

1991 ◽  
Vol 69 (5) ◽  
pp. 794-797 ◽  
Author(s):  
Giuseppina Castronuovo ◽  
Vittorio Elia ◽  
Michela Magliulo
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Chiral Recognition ◽  
Excess Enthalpy ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Calorimetric Study ◽  
Experimental Uncertainty ◽  
Enthalpies Of Dilution

Cross-homo- and cross-heterotactic enthalpic coefficients, [Formula: see text] respectively, were determined at 25 °C, measuring the enthalpies of dilution of ternary aqueous solutions containing two different α-amino acids of the same or different chirality. Differences of about 200–300 J mol−2 kg between cross-homo- and cross-heterotactic coefficients were found, well beyond the experimental uncertainty. The role of the zwitterionic interaction, already proposed to explain the nature of chiral recognition, was strengthened. Key words: α-amino acids, excess enthalpy, chiral recognition.

Electrostriction volumes of α-amino acids from density measurements in water and in aqueous HCl and NaOH solutions at 25 °C

1993 ◽  
Vol 71 (12) ◽  
pp. 2150-2154 ◽  
Author(s):  
M. Abbate ◽  
G. Castronuovo ◽  
V. Elia ◽  
S. Puzziello
Keyword(s):  
Amino Acids ◽  
Hydrochloric Acid ◽  
Aqueous Solutions ◽  
Sodium Hydroxide ◽  
Volume Change ◽  
Pure Water ◽  
Partial Molar Volumes ◽  
Molar Volumes ◽  
Density Measurements ◽  
Alkyl Chains

The values of the limiting partial molar volumes, [Formula: see text], for some α-amino acids bearing alkyl chains, in pure water and in aqueous solutions of hydrochloric acid and sodium hydroxide, have been obtained from density measurements. From these data it is possible to determine the volume change, ΔVZW, due to the formation of the amphionic molecule from the corresponding neutral molecule.

Poly(N-octyl-4-vinylpyridinium bromide) copolymers in aqueous solutions: potentiometric and thermodynamic studies

e-Polymers ◽  
2018 ◽  
Vol 18 (6) ◽  
pp. 551-558 ◽  
Author(s):  
Lahcene Tennouga ◽  
Wassila Bensalah ◽  
Ali Mansri
Keyword(s):  
Free Energy ◽  
Aqueous Solutions ◽  
Radical Polymerization ◽  
Potentiometric Titration ◽  
Hydrophobic Interactions ◽  
Critical Concentration ◽  
Thermodynamic Studies ◽  
Alkyl Chains ◽  
Electrostatic Effect ◽  
Variation Versus

AbstractIn this work, the P4VP was synthesized by radical polymerization. The quaternization of this polymer by octyl bromide leads to the two copolymers [poly(N-octyl-4-vinylpyridinium bromide] named P4VPC8Br 48.8% and P4VPC8Br 72%. The thermodynamic behavior associated with the potentiometric titration of the copolymers, was reported in the temperature range (293.16–333.16 K) and as a function of the concentrations (0.25×10−4 mmol/dm3 12.3×10−4 mmol/dm3). The free energy of dissociation ΔGdiss variation versus the neutralization degree shows the negative value due to the steric and electrostatic effect of the alkyl chains. The positive values of ΔH and ΔS confirmed the spontaneity and disorder of the reaction. The critical concentration C* of the two copolymers was determined from the enthalpy ΔH0 and entropy ΔS0 changes. The transition in conformation of the copolymer chains was influenced by the presence of hydrophobic-hydrophilic and hydrophobic-hydrophobic interactions.

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